Extraction and drying optimisation for producing instant rosehip tea

Rosehip fruit is one of the main L-ascorbic acid (AA) sources. The fruits are processed into marmalade and nectars or dried as whole to prepare rosehip tea either directly in boiling water or commercially packing in tea bags with hibiscus after crushed and separated the fruit flesh. In rosehip however, AA is very sensitive to environmental factors such as heat and light, and it is rapidly degraded during the course of processing, storage, and preparation steps. Especially, in tea bag, active components of the rosehips and hibiscus cannot be utilized sufficiently. In this study, the blend of rosehip fruit, and hibiscus in commercial proportion was extracted, concentrated and spray-dried to produce instant rosehip tea. Each of these processes was optimized to obtain maximum active substances of rosehip and hibiscus and optimum process conditions were estimated and experimentally validated. It was determined that the optimum extraction conditions are 5.3% solid content, 5.4 min and 64°C, while optimum spray drying conditions are 130°C inlet and 85°C outlet air temperatures, and maltodextrin concentration of 18.44% in feed solution. The AA and total monomeric anthocyanins (TMA) content of the instant rosehip tea produced at the optimized conditions are 0.92 g/100 g dry weight and 1.11 g/100 g dry weight, respectively. In addition, soluble rosehip tea produced in the optimal conditions was stored for 90 days at two different temperatures and %55-65 relative humidity. During the storages, the AA and TMA losses at 4°C was markedly lower than that of 25°C. Moreover, phenolic composition of the instant rosehip tea was found to be similar to phenolic composition of the dried rosehip. Although the newly developed product contained high amount of active components, it has caking problems during the storage and according to sensory panels, turbidity, color and flavor characteristics of the product need to be improved.